1. Field of the Invention
The present invention relates to thermal barriers useful in building construction, appliance manufacturing, textiles and other insulation applications, and methods of making and using same. The present invention is particularly directed to thermal barriers containing energy absorbing, temperature stabilizing material for use in buildings, in housewares, and in textile products.
2. Background of the Invention
Insulation is typically used in walls and ceilings of buildings, walls of home appliances and other applications to prevent heat from being conducted either into or out from an enclosed environment so that a desired temperature can be maintained inside. Insulative materials for buildings, appliances and other applications often utilize dead air space present within the materials to insulate from hot or cold environments. The efficiency of such insulating materials generally depends on the amount of dead air space present within the insulative materials, there generally being a direct correlation between the volume of dead air space in conventional insulative material and a particular material's insulating capacity. Because of this correlation, many of the commonly used insulative materials are bulky and difficult to install. Moreover, many such insulative materials lose their insulative capabilities and contribute undesirably to the transfer of heat into or out of an enclosure when the dead air space of the insulative material is compressed or thermally penetrated by convection, conduction or radiation. Conventional insulating materials typically lose their ability to insulate when they become wet, due to the fact that moisture in the insulating materials increases the thermal conductivity of the materials.
Because these problems of bulkiness and insulation failure are typically experienced with traditional insulative materials, there has been a long-felt need for thinner, flexible, thermally effective insulative materials which can block the flow of heat from or to an enclosed environment under a variety of temperature conditions. Prior attempts to develop insulation having the aforementioned qualities have utilized compressed carbon, perlite, fiberglas.TM. and various foams None of these attempts have resulted in a thin, flexible, thermally effective insulative material which can compete with or surpass the effectiveness of traditional insulation.
U.S. Pat. No. 5,290,904 to Colvin et al. issued Mar. 1, 1994, describes a thermal shield incorporating thermal energy absorbing material positioned between two substantially flat flame resistant covering layers. The thermal energy absorbing material may be a phase change material positioned between the covering layers "in bulk" or placed between the covering layers in a micro- or macro-encapsulated form.
However, under certain conditions the thermal energy absorbing material of thermal shield laminates may become displaced. Displacement of the thermal energy absorbing material can result in discontinuities in the thermal shield, with undesired heat transfer subsequently occurring across the thermal shield.
U.S. Pat. Nos. 5,254,380, 5,211,949, 5,282,994 and 5,106,520 for "Dry Powder Mixes Comprising Phase Change Materials" to Salyer describe free flowing, conformable powder-like mixes of silica particles and a phase change material which the silica particles of between 7.times.10.sup.-3 to 7.times.10.sup.-2 microns are mixed with phase change material in a ratio of up to 80% by weight of phase change material. However, under certain conditions the powders described in the Salyer patents may also become displaced. Under these and other circumstances, heat may preferentially flow through gaps of an item in which the powder has become displaced or is otherwise unevenly distributed, resulting in undesirable heat transfer.
It is against this background that the significant improvements and advancement of the present invention have taken place in the field of thermal barriers.